×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Problem of excessive element distortion in ALE adaptive meshing

Problem of excessive element distortion in ALE adaptive meshing

Problem of excessive element distortion in ALE adaptive meshing

(OP)
Hi
My friends

In my model, which is suction of a gel to a pipette, the step visco fails to converge and yields the error of "too many attempts "at the beginning or middle of the procedure which is likely due to "excessive element distortion".
Tricks like altering *CONTROLS will only delay the inevitable as a friend truly said.

As much as I have perceived, Dynamic Explicit is the a good way in combination with ALE adaptive meshing to tackle element distortion problem. It is clear that it helps the process to go further but it still fails due to distortion!!! and gives the following error:

" There are a total of 2 excessively distorted elements The elements contained in element set ErrElemExcessDistortion-Step1 have distorted excessively."

How do you recommend me to change and adjust the Adaptive meshing parameters like frequency, number of sweeps and if it helps to use adaptive mesh controls to get rid of this problem? I tried various values for these frequency and number of sweeps but the problem still exists with a little temporal shift.
I am not very familiar with this topic and Abaqus manual was somehow vague in this regard.
Is ALE adaptive ineffective in solving my case and I have to try another way?

Links to photos that may help to have a schematic imagination of the model:
1-    http://files.engineering.com/getfile.aspx?folder=b701fb87-7f6e-4d16-9700-63d1623e7cec&file=1.JPG

2- http://files.engineering.com/getfile.aspx?folder=55bd768e-91cc-40f4-9949-34b896f2b9c2&file=2.JPG

Many thanks in advance
 

RE: Problem of excessive element distortion in ALE adaptive meshing

I've had the same problem before. Waiting fot the answer. :)

Forever Young.....

RE: Problem of excessive element distortion in ALE adaptive meshing

(OP)
I will let you know the possible solution as soon as i have reached any answer,But till now the problem is still ambiguous and nobody seems to have an opinion toward this matter:D

RE: Problem of excessive element distortion in ALE adaptive meshing

What about export the lasted shape as igs or step file, remesh it, and restart the analysis at that point

Forever Young.....

RE: Problem of excessive element distortion in ALE adaptive meshing


For large deformations you should try to design the mesh such that the element distortion is minimized.

Also, you should try to reduce the frequency for ALE.
 

RE: Problem of excessive element distortion in ALE adaptive meshing

(OP)

Hi!
Dear williwang
The method which you mentioned(Mesh to mesh solution mapping )is,as far as I know,not a very time-friendly one,besides I am not familiar with that process.I have put it aside as the last card when all the other otions failed to answer.I am still experimenting ALE and will let you know my discoveries!
 
 

RE: Problem of excessive element distortion in ALE adaptive meshing

(OP)
Hi!
Dear Xerf

For the 1st point,I am of the opinion that your model should answer regardless of the mesh type you choose,
yeah;using tri elements or a coarser mesh help but why shouldn't I be able to elicit answer with quad for example?
So I guess that the fundamental problem lies somewhere else.

And for the 2nd,
I am not very sure now but as I highly increase the frequency it goes further without any error! But as the solution time was very long I am still not sure about the results. I will let you know the outcome.
Regards
 

RE: Problem of excessive element distortion in ALE adaptive meshing

What I wanted to say is that you should request the adaptive meshing procedure to occur more often. However, this is typically more computationally expensive. I think each time the adaptive meshing is called, it takes as much as solving for several explicit increments.

If I am not wrong, for the FREQUENCY parameter one specify the number of time increments after which the adaptive meshing is called. Therefore, by decreasing its value, the adaptive meshing will be applied more often.

Best.

RE: Problem of excessive element distortion in ALE adaptive meshing

(OP)
Dear Xerf
Your idea initiated some doubt,I will check this.
Thanks dear,
Bests

RE: Problem of excessive element distortion in ALE adaptive meshing

(OP)
Dear Xerf

As much as I have understood, increasing the frequency will request the adaptive meshing procedure to occur more often and therefore distortion will be procrastinated.

But in my case I think that distortion is inevitable since the loading is introduced to be instantaneous which means a huge load applied in a very short time interval and therefore an impact which makes the elements to distort.
As I have to introduce the load instantaneously and not as a ramp , I have to find a cure for this case.

Regards

RE: Problem of excessive element distortion in ALE adaptive meshing

(OP)
It seems that I have finally understood what my problem is.My load is instantaneous,therefore excessive distortion is inevitable.I have to substitute this with a ramp load.Increasing frequency also helps to prevent distortion as far as I have understood.Another interesting matter is mass scaling.It helps you to reduce computational costs.You can increase it as much as the kinetic energy of the system in a transient(quasi-static)remains negligible in comparison with the internal energy.

Thank you all my friends for your ideas and contributions,
Regards

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources